Compounds of the general structure I ##STR1## wherein Ar represents an aromatic (substituted or unsubstituted) or heteroaromatic (substituted or unsubstituted) ring system wherein the substituents are electron withdrawing functional groups in combination with other organic functional groups are exceptionally active herbicides and are active in the suppression of nitrification of ammonium nitrogen in soil and are effective in beneficially regulating the growth of crops and are readily produced. The aromatic ring may be monocyclic containing six carbon atoms or bicyclic containing ten carbon atoms. The heteroaromatic ring may be monocyclic containing five or six atoms or bicyclic containing nine or ten atoms. The heteroatoms present in the heteroaromatic ring may be one combination of one or more atoms such as nitrogen, oxygen, or sulfur.
Compounds in this family have been prepared by a conventional reaction between an appropriate substituted aniline and a substituted 1,2,4-triazolo-[1,5-a]-pyrimidine-2-sulfonyl chloride under basic conditions, as described in European patent application 142,152. However, it is difficult to prepare many analogs in high yield due to the poor compatability of the heterocycle substituents (X, Y, and Z) to the reaction conditions for the preparation of the sulfonyl chloride or the subsequent sulfonamide (I).